This invention relates to fluid disinfection systems. In particular, the invention relates to using a modular ballast enclosure to power lamp modules for the ultraviolet (hereinafter xe2x80x9cUVxe2x80x9d ) disinfection of water and wastewater.
Historically, the most widely used technique for purifying large quantities of water has been the addition of small quantities of chlorine or chlorine releasing compounds to the water, sufficient to destroy undesirable micro-organisms. However, chlorination tends to render the water less acceptable for drinking or bathing, particularly if the chlorine concentration and pH of the water are not carefully controlled. Furthermore, chlorine may interact with other compounds present in the water to leave low concentrations of possibly harmful chemicals.
Recently, it has become popular to introduce UV light into a fluid channel for water purification purposes. It has been known for many years that UV light at appropriate wavelengths has powerful germicidal properties. Using UV light avoids the disadvantages associated with chlorination mentioned above. However, wastewater disinfection systems utilizing UV treatment of wastewater, such as industrial and municipal wastewater, rely on complex systems presenting a wide variety of problems and challenges. The problems associated with such complex systems are enhanced in view of the wide span of engineering and scientific disciplines encountered, such as civil and electrical engineering, computer hardware and software design, biology, chemistry and the like, in the design and construction of effective treatment systems. Most of the problems associated with such treatment are problems of implementation, such as finding equipment which is readily and economically maintained. Other problems include difficulties in designing and constructing low maintenance and/or easily serviceable UV disinfection systems.
For example, it is known that radiation from UV light producing lamps utilized in UV disinfection systems decreases with time. There is typically a rapid drop in radiation during the first 100 hours of operation. Following this initial period, the decline in efficiency continues but at a much slower rate. After approximately 8800 hours of xe2x80x9conxe2x80x9d service, or about one year of continuous operation, lamp efficiency drops to about 65% of its efficiency after the first 100 hours and typically no longer provides sufficient intensity to achieve the desired degree of disinfection. At this point, to maintain operating efficiency, the system lamps are usually replaced. Most UV installations replace lamps yearly to ensure adequate wastewater disinfection. Some lamps are replaced before they have been in xe2x80x9conxe2x80x9d service a full year. For example, the use of control schemes, which turn banks of lamps on and off in response to changes in wastewater flow to minimize electrical power consumption, tends to reduce filament life. Generally, however, a standard lamp has a filament life of 2000-3000 on-off cycles after which time the lamp must be replaced.
The need to frequently replace lamps is further compounded by the problem that the lamps are submerged in a moving body of water, typically an open channel, which should remain continuously operational to maximize efficiency. Removing lamps or banks of lamps from the wastewater flow can lead to significant efficiency losses due to water treatment stoppage, added personnel costs and the like.
U.S. Pat. No. 5,368,826 to Weltz et al. has attempted to address these problems by providing control apparatus for wastewater disinfection systems which permit fewer lamp replacements, reduce personnel requirements, minimize maintenance monitoring and curtail electrical consumption. However, regardless of the control system employed, the lamp units inevitably will degrade or fail and will need to be replaced.
U.S. Pat. No. 4,757,205 to Latel provides a system that purports to facilitate replacing the lamp units in a UV disinfection system. In particular, the ""205 patent shows an ultraviolet water treatment plant in which individual ultraviolet lamps are loosely and retractably located within frames or xe2x80x9clamp modulesxe2x80x9d supported in a water treatment channel. Individual lamp modules supporting arrays of parallel lamp units may be removed from the channel, and the lamp units may be individually disengaged from the frame and disassembled for lamp replacement. The frames have unitary plug connectors to a power supply arranged so that the plug of a frame must be disengaged before that frame can be removed from the channel. However, the weight of the lamp modules in such as system makes it difficult to remove the modules when the lamps need replacement.
One element that comprises a substantial portion of the overall weight of the lamp module is a ballast. Although not disclosed in the ""205 patent, it is known in the art that a ballast must be provided in the disinfection system to control the power to the lamp modules. For example, FIG. 1 of U.S. Pat. No. 5,006,244 to Maarschalkerweerd shows a ballast 2 for controlling the voltage and amperage through the ultraviolet lamps 14. To initially energize the lamps, high voltage on the order of 600 volts at the ballast is required, but once the lamps are energized, a lower voltage, for example, 180 volts at the ballast is sufficient. This variation of voltage is provided by the ballast. The ballast also functions to limit the amperage through the lamps.
In most UV disinfection systems, such as the system disclosed in FIG. 1 of the ""244 patent, the ballast is mounted to the frame legs of the lamp module. However, incorporating the ballast into the lamp module frame adds significant weight to the lamp module making the module heavy and difficult to manage. Due to the ballast being located on the lamp module frame, these lamp modules typically weigh between 30-50 lbs and require special lifting equipment for removing the module from a channel.
Some prior art systems have attempted to solve this problem by manufacturing lightweight lamp modules and locating the ballast in a control panel. However, the control panels in these systems necessarily must be custom designed to service a specific number of lamp modules. For example, if a six lampxe2x80x94system is desired, a custom control panel would be manufactured for the system, including a fixed number of ballasts to supply power to each module. If at a later time, the system needs to be modified to accommodate an additional lamp module, the control panel would need to be completely re-wired and, most likely, would structurally need to be modified to accommodate the additional ballasts. Thus, custom control panels are not cost effective to manufacture since each panel must be designed and manufactured according to the number of lamp modules in the system. Furthermore, since it is known in the art that the distance between the ballast and the lamp module should be minimized for proper performance, the control panel would need to be located near the lamp modules it services. Thus, such an arrangement prohibits remote placement of control panels in a central location and imposes an undesired restriction on installation of the system.
Neither of these prior art schemes are suitable for both cost effective modular production of UV systems and easy servicing of the system. The present invention reduces the complexities associated with manufacturing customized systems while providing for easy servicing of the lamp modules and associated ballasts. Since the ballasts are located in separate modular ballast enclosures, the invention accommodates a variety of different lamp configurations according to user-defined system requirements. Furthermore, by adding or removing modular ballast enclosures and lamp modules, a disinfection system of the invention can be easily re-configured on an as-needed basis. In addition, the modular aspect of the invention provides for ease of manufacturing in an assembly line manner, as opposed to custom designs of the prior art, and eliminates the need for cumbersome, heavy lamp modules which can be expensive and difficult to handle.
The invention relates to a disinfection system for fluids in a channel. The disinfection system includes a lamp module and a modular ballast enclosure. The lamp module has at least one lamp, but preferably, has a plurality of lamps. The modular ballast enclosure is preferably constructed of a thermally conductive material and is located adjacent to the channel. The enclosure has an enclosure wall, a ballast for powering the lamp module, and a receptacle on the modular ballast enclosure adapted to receive a connection from the lamp module. In one preferred embodiment of the invention, the ballast enclosure is preferably substantially environmentally sealed. Other embodiments may comprise one or more of the following: a ballast, circuitry for monitoring lamp and module status, such as, for example, at least one LED to display the status of each lamp, ground fault circuit interrupter(s), a power source, and a power connector (preferably a multi-pin connector) adapted to receive power from the power source.
A modular ballast enclosure of the invention preferably has a width substantially equal to a width of the lamp module. For example, a lamp module designed to be three inches wide for three inch spacing of the UV lamps preferably has a corresponding ballast enclosure that is three inches wide in order to visually line up with the module and be installed in close proximity to the module. Ballast enclosures are preferably environmentally rated and suitable for indoor or outdoor installation. At least a portion of the ballast unit wall should be thermally conductive and substantially adjacent to the lamp module and the fluid channel.